Reference is made to the following pending U.S. patent applications which were filed on the same date the instant application was filed, are owned by the assignee of the present application, and which relate to the same commercial apparatus on which this instant invention is empolyed: Ser. Nos. 807,553, 807,573, 807,617 and 728,511.
1. Field of the Invention
This invention relates to a material handling vehicle and, more particularly, to a material handling vehicle having a lower truck chassis which includes a truck cab and an upper structure which includes an upper cab and a material handling implement, such vehicle having a single engine on the lower chassis which provides power for operation under the control of an operator in either cab.
2. Description of the Prior Art
Frequently, a heavy duty material handling vehicle such as a crane or excavator includes a lower or truck chassis on which is horizontally pivotally mounted an upper structure that supports the desired material handling implement. The truck chassis is capable of being driven over the road or highway under the control of an operator in the main truck cab. An upper structure is mounted on the truck chassis by a swing bearing through which a center pin extends for relative movement with respect to the truck chassis. An upper structure operator's cab is provided on the upper structure to move with a material handling boom and implement. During operation at a contruction site, an operator in the upper structure operator cab can control movement of the truck chassis and also the material handling mechanism.
Heretofore, in order to provide for remote operation from the upper structure cab of both the manipulations of the material handling mechanism as well as the movement of the entire vehicle, two separate engines were required. One engine was mounted on the truck chassis and controlled the highway operation of the vehicle. A separate engine was mounted on the upper structure and provided motive power both to the material handling mechanism as well as powering, through a hydraulic pump and motor, the motion of the truck chassis. U.S. Pat. No. 3,599,814 teaches a remote drive mechanism for powering the drive wheels from an auxilliary engine mounted on the upper structure. U.S. Pat. No. 4,318,451 also teaches a material handling vehicle having a power supply on the upper structure which through a hydraulic motor drives the vehicle at the job site.
As is well known in the art, the previously unavoidable requirement of two separate engines, one on the truck chassis and one on the upper structure, was fraught with a host of disadvantages. For example, with the prior art construction requiring two separate engines the additional weight and cost of the auxilliary engine itself as well as duplicate fuel tanks, radiators, battery and charging systems, air compressors and dryers, power steering pumps, air cleaners and exhaust systems, controls, shroudings and mountings, noise barriers, engine gauges, etc., are incurred. In addition, duplicate maintenance functions are involved in a two-engine vehicle and operating costs are necessarily increased. Further, the inclusion of the second engine and hydraulic reservoir on the movable upper structure raises the center of gravity of the material handling vehicle. Such a high center of gravity imposes engineering and operating restrictions which are considerable.
The subject invention is directed toward an improved material handling apparatus which overcomes, among others, the above-discussed problems with material handling vehicles which employ two engines, one for on-road travel and one for remote operation controlled from an upper cab, which is effective to sufficiently power all customary remotely controlled functions of a material handling apparatus while requiring only one engine.